Abstract 18459: MicroRNA-712 Induced by Angiotensin II Plays a Key Role in Development of Abdominal Aortic Aneurysm in Mouse

Abstract

Abdominal aortic aneurysm (AAA) is a complex vascular disease and a major cause of mortality. AAA is characterized by a weakening of the vessel wall, followed by progressive expansion of the diseased aortic segment. Although the molecular mechanisms underlying AAA initiation and development are poorly understood, microRNAs (miRNAs) are thought to play a role in these processes. Here we identify microRNA-712 (miR-712) through a microRNA array study as a novel miRNA upregulated in abdominal aortic endothelium in mice infused with angiotensin II (AngII, 1 ug/kg/min for 12 to 36 hours). Through in silico analysis and using gain-of-function [pre-miR-712] and loss-of-function [locked nucleic acid (LNA)-based anti-miR-712] studies, we determined that miR-712 directly regulates the expression of tissue inhibitor of metalloproteinase 3 (TIMP3). Additionally, we confirmed the target-binding activity of miR-712 on the 3’UTR of TIMP3 by dual-luciferase reporter assay. Furthermore, inhibition of miR-712 decreased matrix metalloproteinase (MMP) activity in an AngII-infused abdominal aorta wall. Finally, we showed that inhibition of AngII-induced miR-712 by subcutaneous injection of anti-miR-712 reduced AAA incidence from 80% (8/10) to 20% (2/10) and maximal aortic diameter from 2.1±0.6mm to 1.2±0.4 mm compared to mismatched control in ApoE -/- mice via MMP-mediated mechanisms. Our findings show that miR-712 regulates MMPs activity through the endogenous regulator TIMP3, which leads us to conclude that AngII-induced miRNAs such as miR-712 play important roles in the pathogenesis of AAA. These results suggest that manipulation of miR-712, and its target gene TIMP3 may hold promise as a therapeutic strategy to prevent the development of AAA.